Electric contact clamp



P 1964 J. R. HARMON ETA]. 3,

ELECTRIC CONTACT CLAMP Filed May 31, 1962 VINVENTORS JAMES R. HARMON HAROLD G.SCHNE|DER United States Patent 3,129,994 ELECTRIC CONTACT CLAMP James R. Harmon, 6845 SW. 17th St., Miami, Fla., and Harold G. Schneider, 8867 Carlyle Ave., Surfside, Fla. Filed May 31, 1962, Ser. No. 198,867 3 Claims. (Cl. 33995) This invention relates in general to electric ground clamps and more particularly to an adjustable clamp for tightly securing conductors to metal conduits of a Wide range of diameters.

Ground clamps prior to this invention depended upon a plurality of pierced holes in the strap thereof for adjusting same to conduits of different diameters. The conventional screw means for engagement with the aforesaid holes not only limited the range of adjustment but also limited the strength of the strap and the resultant security of contact with the conduit.

The present invention overcomes the above objections and disadvantages by the provision of the combination of straps and screw means wherein a key is used to forcibly Wrap the strap when in tightened position and securely engage the conduit for forming a secure terminus for a ground conductor and is a principal object of the invention.

A further object of the invention is a ground clamp for conduits including a body member, a strap, and a key for securely wrapping the strap around the conduit including a screw means in said body for piercing and retaining the strap in a tensioned position around said conduit.

Reference is had to US. patent application Serial No. 179,439, now Patent No. 3,094,366.

These and other objects and advantages in one embodiment of the invention are described and shown in the appended specification and drawing in which:

FIG. 1 is a side view of the ground clamp attached to a conduit.

FIG. 2 is a side view of the clamp shown in FIG. 1.

FIG. 3 is a fragmentary cross sectional elevation taken through the clamp shown in FIG. 2.

FIG. 4 is the same as FIG. 3 with elements in changed position.

Referring to FIGS. 1 and 2, the ground clamp comprises a hollow rectangular body member 1 with a flexible metal strap 2 secured by one end 3 to a lower portion of body 1 as shown. The opposite end portion 4 is engaged in the slotted end of a conventional key 5 having a slotted shank, for manual finger rotation against the side of body 1 for clamping the strap around the outer periphery of conduit 6. Referring to FIGS. 3-4, a screw 7 having a pointed lower end is threaded through the body 1 as shown and when the strap 2 is clamped around the conduit 3 a bend 8 around the corner of portion 3 will temporarily hold the strap in clamped position. When the screw 7 is tightened the pointed end thereof will pierce the strap 2 and move through a hole in portion 3 and into the lower portion of body 1 and embed itself into the outer surface of the conduit. A terminal 9 or a bare conductor is then clamped under nut 10 which serves the dual purpose of securing the conductor or terminal to the body 1 and to serve as a lock nut for holding the screw in clamped position. It is apparent that the surplus strap and the key may be cut oii at 11 and discarded as shown FIGS. 3 and 4.

It is understood that certain modifications in the above construction, utilizing the features described, are intended to come within the scope of the appended claims.

Having described our invention, we claim:

1. An electric ground clamp for a conduit for retaining a conductor comprising a terminal screw with one end thereof terminating in a piercing point and the opposite end thereof terminating in a head,

a hollow rectangular body member threaded through opposite sides thereof and adapted to adjustably retain said screw for axial movement therethrough into contact with said conduit when driven by said head,

a flexible band having one end thereof secured to said member and adapted to encircle said conduit with the opposite end portion thereof positioned through and extending from said member between the threaded sides thereof and in overlapping position with respect to said one end,

a key means having an axial slot therein engaged with the said opposite end of said band transverse thereto whereby the manual finger rotation of said key will wind said band thereon in oblique position against one side of said member and tension said band around said conduit and whereby said point of said screw will pierce said opposite end portion of said band and engage said conduit for securing said clamp to said conduit when said head is driven.

2. The construction recited in claim 1 including said one end having a pre-pierced hole therein for engagement by said screw when the latter has pierced said band.

3. The construction recited in claim 1 including a screw thread means associated with said member for securing said conductor to said member.

References Cited in the file of this patent UNITED STATES PATENTS 972,489 Adams Oct. 11, 1910 1,505,314 Cox Aug. 19, 1924 1,675,163 Colburn June 26, 1928 2,158,802 Redlon May 16, 1939 FOREIGN PATENTS 175,085 Great Britain Feb. 16, 1922 233,116 Great Britain May 7, 1925 834,091 Great Britain May 4, 1960 40,573 France Apr. 19, 1932 

1. AN ELECTRIC GROUND CLAMP FOR A CONDUIT FOR RETAINING A CONDUCTOR COMPRISING A TERMINAL SCREW WITH ONE END THEREOF TERMINATING IN A PIERCING POINT AND THE OPPOSITE END THEREOF TERMINATING IN A HEAD, A HOLLOW RECTANGULAR BODY MEMBER THREADED THROUGH OPPOSITE SIDES THEREOF AND ADAPTED TO ADJUSTABLY RETAIN SAID SCREW FOR AXIAL MOVEMENT THERETHROUGH INTO CONTACT WITH SAID CONDUIT WHEN DRIVEN BY SAID HEAD, A FLEXIBLE BAND HAVING ONE END THEREOF SECURED TO SAID MEMBER AND ADAPTED TO ENCIRCLE SAID CONDUIT WITH THE OPPOSITE END PORTION THEREOF POSITIONED THROUGH AND EXTENDING FROM SAID MEMBER BETWEEN THE THREADED SIDES THEREOF AND IN OVERLAPPING POSITION WITH RESPECT TO SAID ONE END, A KEY MEANS HAVING AN AXIAL SLOT THEREIN ENGAGED WITH THE SAID OPPOSITE END OF SAID BAND TRANSVERSE THERETO WHEREBY THE MANUAL FINGER ROTATION OF SAID KEY WILL WIND SAID BAND THEREON IN OBLIQUE POSITION AGAINST ONE SIDE OF SAID MEMBER AND TENSION SAID BAND AROUND SAID CONDUIT AND WHEREBY SAID POINT OF SAID SCREW WILL PIERCE SAID OPPOSITE END PORTION OF SAID BAND AND ENGAGE SAID CONDUIT FOR SECURING SAID CLAMP TO SAID CONDUIT WHEN SAID HEAD IS DRIVEN. 